A few weeks ago, we made our final offer to the joint unions about the way forward on pension reform. As a result of that offer, the union leaders agreed to call off the planned industrial action and said that they would present the offer to their members as the best that could be achieved in the circumstances.

Since then, the agreement has been ratified by members of four out of the five BBC unions, including Bectu, the largest union in the BBC. The NUJ, by contrast, have announced two 48-hour strikes, the first of which will begin this Friday. They have done this on the basis of a consultative ballot, the turnout for which they have refused to disclose to anyone – including their own members and representatives.

NUJ membership represents some 17% of the BBC workforce. We do not know how many NUJ members voted to reject the agreement in the consultative ballot but it was almost certainly a minority of the total NUJ membership – and certainly a very small percentage of the BBC workforce as a whole.

I want to make three points about this week's planned industrial action. The first is that I believe that the package on pension reform which we have arrived at is a fair one and that it has changed in significant and positive ways as a result both of our consultation with staff and our discussions with the unions. To have gone further would have been to risk damage to the quality of our services to the public and to jobs. The proposals we agreed with the unions some weeks ago were and will remain the BBC's final offer.

Some have argued that it would have been better if the whole question of pension reform had waited until after the formal valuation of the pension deficit had taken place. But the whole point of introducing the reforms now was so that the reforms could themselves be taken account of in the valuation process. As a result of the reforms, the deficit will be significantly lower than it otherwise would have been and the BBC's payments to eliminate that deficit will also be lower. Had we waited, the impact on services and jobs across the BBC would have been much worse.

The second point is that, while I recognise the legal right of NUJ members to go on strike, I also feel obliged to say that I cannot see what earthly good such action is going to achieve. They may manage to take some output off the air or lower its quality. But strikes aren't going to reduce the pension deficit or make the need for radical pension reform go away. The BBC couldn't change its current position without breaking faith with the other trade unions and we just will not do that no matter how many strikes there are. For NUJ members, it will mean significant loss of earnings without any advantage or benefit in return. And the public – many of whom are facing difficult employment and economic pressures – will find it very hard to understand why the BBC's service to them should be impaired in this way.

The last thing I wanted to say is that, while I understand that a decision to cross a picket-line is a difficult and personal one, we do expect all non-NUJ staff to come to work on these strike days. This is also the advice being given to members of other BBC unions by their own leadership. People who strike or those who choose not to cross picket lines will lose pay for the relevant day. The BBC belongs to the British public and has a duty to deliver programmes and services of the highest quality to them every day of the year. They rely on us. We must not let them down.